The focus of this grant is the development of a device for the treatment of ischemic stroke; a potentially lethal problem that occurs when a blood clot (thrombus or embolus) blocks an artery delivering oxygenated blood to the brain. More than 85% of strokes are ischemic and these strokes affect more than 2 million people in the developed world each year, including 615,000 in the United States in 2003. Currently, the prognosis for those who suffer from an ischemic stroke is poor - approximately 20% die shortly after the initial stroke and most survivors require full or part-time care. The total costs associated with stroke, including acute and chronic care, rehabilitation and indirect costs, are estimated at about $50 billion annually in the U.S. The aim of the proposed research is the design and construction of a medical device that treats ischemic stoke patients by virtue of breaking-down endovascular blood occlusions using Selva Medical Inc.'s proprietary LIFT (Laser Induced Fluid-dynamic Thrombolysis) technology that is a safer and more reliable approach compared to laser ablation treatments. The device consists of a reliable diode-pumped q-switched Nd:YAG laser source, a laser beam delivery module that interfaces with a novel microcatheter that includes fiber optic probes. The catheter tip design will be based on laboratory feasibility studies and guided by advanced simulation. In Phase I we intend to build conseptual prototypes of the catheter tip aided by novel simulation tools and test them in the laboratory using existing lasers. In Phase II we intend to finalize the design, build prototypes and perform laboratory experiments and initial animal studies to verify the final design of the catheter. Our plan is to include human clinical trials in a Phase II continuation grant and commercialize the device thereafter. The instrument should be reliable, maintainable and easy to use by trained medical personnel. It will be capable of operation within the 6-hour window required for patient treatment from ischemic stroke. It will be capable of basic treatment within 10 minutes of starting operation. [unreadable] [unreadable]